1. Field of the Invention
The present invention relates to a display device and an electronic machine having the display device. The display device has a backlight light source and a photo sensing unit capable of detecting the light intensity of ambient light and outputting a photocurrent corresponding to the light intensity of ambient light.
2. Description of Related Art
In recent years, display devices, such as those commonly applied in mobile navigation devices, cell phones, etc, have been capable of allowing the display brightness to be modified corresponding to the intensity of ambient light. For example, the system disclosed in the Japan Publication Patent No. 2001-522058, which disclosed a controller for controlling the display brightness of the display device, bases on the result of light intensity of ambient light detected by the photo sensing unit. By having this controller, the system can increase the display brightness of the display device at an outdoor place with bright sunlight, and decrease the display brightness of the display device at an indoor place, where the ambient light is weak.
In general, the display device has a photo sensing unit, which outputs a photocurrent based on the detection result on the light intensity of ambient light. Later, by means of a current-voltage transformer or an analog-digital transformer, the photocurrent is transformed into a voltage or digital pulse signal, being output to a controller controlling the operation status of the backlight light source. The controller then modulates the light intensity of the backlight light source of the display device based on the input voltage or digital pulse signal. A circuit used for the aforementioned light intensity detection is disclosed in the Japan Publication Patent No. 2008-522159.